Immune responses to typhoid conjugate vaccine in a two dose schedule among Nepalese children <2 years of age.
Vaccine
; 42(8): 2018-2025, 2024 Mar 19.
Article
en En
| MEDLINE
| ID: mdl-38395723
ABSTRACT
BACKGROUND:
Previously, the Vi-typhoid conjugate vaccine (Vi-TT) was found to be highly efficacious in Nepalese children under 16 years of age. We assessed the immunogenicity of Vi-TT at 9 and 12 months of age and response to a booster dose at 15 months of age.METHODS:
Infants were recruited at Patan Hospital, Kathmandu and received an initial dose of Vi-TT at 9 or 12 months of age with a booster dose at 15 months of age. Blood was taken at four timepoints, and antibody titres were measured using a commercial ELISA kit. The primary study outcome was seroconversion (4-fold rise in antibody titre) of IgG one month after both the doses.FINDINGS:
Fifty children were recruited to each study group.Some visits were disrupted by the COVID19 pandemic and occurred out of protocol windows.Both the study groups attained 100 % IgG seroconversion after the initial dose. IgG seroconversion in the 9-month group was significantly higher than in the 12-month group (68.42 % vs 25.8 %, p < 0.001). Among individuals who attended visits per protocol, IgG seroconversion after the first dose occurred in 100 % of individuals (n = 27/27 in 9-month and n = 32/32 in 12-month group). However, seroconversion rates after the second dose were 80 % in the 9-month and 0 % in the shorter dose-interval 12-month group (p < 0.001) (n = 16/20 and n = 0/8, respectively).INTERPRETATION:
Vi-TT is highly immunogenic at both 9 and 12 months of age. Stronger response to a booster in the 9-month group is likely due to the longer interval between doses.Palabras clave
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Fiebre Tifoidea
/
Vacunas Tifoides-Paratifoides
Límite:
Child
/
Humans
/
Infant
País/Región como asunto:
Asia
Idioma:
En
Revista:
Vaccine
Año:
2024
Tipo del documento:
Article